Muscular dystrophy (MD) is a group of hereditary diseases which cause muscle weakness. The genetic basis for MD is the coding of defective proteins which are components of muscle tissue. Although there are over 100 diseases which have similarities to MD, several diseases are commonly grouped together as various forms of MD. These include Becker's, congenital, Duchenne, distal, Emery-Dreifuss, fascioscapulohumeral, limb-girdle, myotonic and oculopharyngeal muscular dystrophies.
One type of muscular dystrophy, known as congenital muscular dystrophy (CMD), is a group of genetic degenerative diseases which primarily affect voluntary muscles. The symptoms of CMD are often noted from birth. CMD may involve weakness of the facial and limb muscles and a generalized lack of muscle tone, any or all of which usually appear before the age of 9 months. CMD may be an autosomal dominant or recessive trait and may be inherited through either or both parents. In some cases, CMD may be the result of spontaneous mutation.
It has been found that regular resistance or assistance training of the arms and legs of infants with CMD considerably enhances the muscular strength and range-of-motion of the infant's arms and legs, facilitating muscular development and mobility of these infants as they mature into childhood.